The synaptic organization, physiological responses and functional role of retinal neurons are fairly well understood. However, little is known about the role of glial cells in retinal function. Recent studies suggest that in the central nervous system, glial cells are not only involved in metabolic function but also play an important role in the differentiation, development and maturation of neurons. The recent development of a method for obtaining large numbers of structurally intact and functionally viable Muller cells provides an opportunity to examine directly the properties of Muller cells in isolation and to understand their interactions with neurons. The purpose of this research proposal is to use both conventional and recently developed methods to study glial function in the development, maturation and maintenance of the vertebrate retina. There are four main objectives: 1. The ionic properties of isolated Muller cells will be studied by both biochemical and electrophysiological methods with particular emphasis on whether Muller cells can act as K+-sensitive electrodes; 2. The role of surface carbohydrates in neuronal-glial interactions will be examined during retinal development and regeneration using lectins as as surface probes; 3. To characterize Muller cell-surface specific antigenic markers, antibodies will be raised against isolated Muller cells and the antiserum will be used to study the surface topography and development of Muller cells; 4. Primary cultures of Muller cells will be developed to facilitate studies of the properties of these cells in vitro. Such cultures will also be used as substrates for maintaining retinal neurons in cultures.